2,4-diamino-substituted pyrido(3,2-d)pyrimidines and salts thereof

ABSTRACT

Compounds of the formula   WHEREIN R1 and R2, which may be identical to or different from each other, are each morpholino, thiomorpholino, 1-oxidothiomorpholino, 1,1-dioxido-thiomorpholino or piperidino, where each of these may optionally have a lower alkyl substituent attached thereto; piperazino; N&#39;&#39;-acyl-piperazino; N&#39;&#39;-carbamoylpiperazino; N&#39;&#39;-lower alkyl-piperazino; dialkanol-amino; or alkylenediamino; and R3 is hydrogen or methyl; AND THEIR NON-TOXIC, PHARMACOLOGICALLY ACCEPTABLE ACID ADDITION SALTS; THE COMPOUNDS AS WELL AS THEIR SALTS ARE USEFUL AS INHIBITORS OF THROMBOCYTE AGGREGATION AND ADHESIVENESS.

limited States Patent [191 Nicki et al.

[ 51 Cot. 22, 19M

[75] Inventors: Josef Nicki; Erich Muller; Berthold Barr; Josef Roch, all of Biberach, Riss, Germany [73] Assignee: Boehringer lngelheim Gmblill,

lngelheim am Rhine, Germany [22] Filed: Apr. 6, 1972 [21] Appl. No.: 241,791

[30] Foreign Application Priority Data Apr. 10, 1971 Germany 2117657 Feb. 23, 1972 Germany 2208534 Feb. 23, 1972 Germany 220 8535 [56] References Cited UNITED STATES PATENTS 2,937,284 5/1960 Hitchings et a1. 260/2564 F 3,248,395 4/1966 Ohnacker 260/2564 F 3,534,039 l0/l970 Davoll 260/256-11 Primary Examiner-Richard .1. Gallagher Attorney, Agent, or Firm-l-lammond & Littell {57] ABSTRACT Compounds of the formula wherein R and R which may be identical to or different from each other, are each morpholino, thiomorpholino, l-oxido-thiomorpholino, 1,1-dioxido-thiomorpholino or piperidino, where each of these may optionally have a lower alkyl substituent attached thereto; piperazino; N'-acyl-piperazino; N'-carbamoyl-piperazino; N'-lower alkylpiperazino; dialkanol-amino; or alkylenediamino; and R is hydrogen or methyl; and their non-toxic, pharmacologically acceptable acid addition salts; the compounds as well as their salts are useful as inhibitors of thrombocyte aggregation and adhesiveness.

8 Claims, No Drawings ll amwaasuasrrwraa PYRIlDO(3,2-]D)PYRIMIDINES AND SALTS THEREOF This invention relates to novel 2,4diaminosubstituted pyrido[3,2-di]pyrimidines and non-toxic acid addition salts thereof, as well as to methods of preparing these compounds.

More particularly, the present invention relates to a novel class of pyrido[3,2-d]pyrimidines represented by the formula wherein one of Z, and Z is a substituent exchangeable for an amino-substituent included in the definition of R, and R in connection with formula I, such as halogen or an alkyl, arylor aralkyl-substituted hydroxy, mercapto, sultinyl or sulfonyl group, the other of Z, and Z has a meaning defined for R, and R in formula I, and R, has the meanings defined in formula I, with an amine of the formula (lll).

respectively, where R, and R have the same meanings as in formula I.

The substituent exchange reaction is carried out, depending uponthe reactivity of the exchangeable substituent Z, or Zhd 2, at a temperature between and +250C, optionally in the presence of an acid-binding agent, and advantageously in a solvent medium, such as dioxane, glycol dimethyl ether or an excess of the amine reactant of the formula III.

In those instances where Z, is halogen or an alkyl-, arylor aralkyl-substituted sulfmyl or sulfonyl group, the reaction is preferably performed at a temperature between 80 and 1 10C; on the other hand, if Z, is an alkyl-, arylor aralkyl-substituted hydroxyl or mercapto group, the reaction is carried out within a preferred temperature range of 150 to 200C, if necessary in a pressure vessel.

In those instances where Z, is halogen or an alkyl-, arylor aralkyl-substituted sulfmyl or sulfonyl group, the reaction is preferably performed at a temperature between 0 and +40C; on the other hand, if 2, is an alkyl-, arylor aralkyl-substituted hydroxyl or mercapto group, the preferred reaction temperature is between and C.

If it is desired to prepare a compound of the formula I wherein R, and R are identical to each other, the starting compound of the formula II may also be one wherein Z, and Z, are both exchangeable substituents, as defined in connection with formula II; in that case the substituent exchange reaction proceeds stepwise. For instance, if the starting compound of the formula II is 2,4-dichloro-6-methyl-pyrido[3,2-d]pyrimidine, the chlorine atom in the 4-position is exchanged for the amino-substituent at temperatures as low as 0 to +40C, while the chlorine atom in the 2-position is not exchanged until more elevated reaction temperatures are applied.

Method B For the preparation of a compound of the formula I wherein one of R, and R, is unsubstituted piperazino andthe other has the meanings defined for R, and R in connection with formula I except N-acylpiperazino, by de-acylating a di or tri-substituted pyrido[3,2-d]pyrimidine of the formula N\ Ru R l /N wherein R, has the same meanings as in formula I, one of substituents R, and R is N'-acyl-piperazino and the other has a meaning defined for R, and R in connection with formula I.

The de-acylation is preferably carried out by hydrolysis in the presence of an inorganic base, such as potassium hydroxide, or of an acid, such as hydrochloric acid, advantageously in a solvent medium, such as water or isopropanol, and at a temperature up to the boiling point of the particular solvent medium.

In those instances where method A or B yields a compound of the formula I wherein R, and/or R are unsubstituted piperazino, these may, if desired, subsequently be acylated by conventional methods. The acylation is preferably effected with a corresponding acid halide or acid anhydride, or with the corresponding acid in the presence of a dehydrating agent, such as N,N- dicyclohexyl-carbodiimide, or in an apparatus provided with a water separator; a carbamoyl substituent is advantageously introduced by reaction with an alkali metal cyanate in weakly acid solution.

' The compounds embraced by formula I are organic bases and therefore form acid addition salts with inorganic or organic acids. Examples of non-toxic, pharmacologically acceptable acid addition salts are those formed with hydrochloric acid, hydrobromic acid. sulfuric acid, phosphoric acid, lactic acid, citric acid, tartaric acid, maleic acid, 8-chlorotheophylline or the like.

The starting compounds needed for methods A and B are either known compounds or may be prepared by methods described in the literature.

For instance, a corresponding 2-chloro-4-aminosubstituted pyrido[3,2-d]pyrimidine of the formula 11 may be obtained by reacting 2,4-dich1oro-pyrido[3,2- d]pyrimidine [see J.A.C.S. 78, 973 (1956); J. Chem. Soc. 1956, 1045; and J. Chem. Soc. 1956, 4433] with a corresponding amine at relatively low temperatures, such as to 40C [see also W. .1. lrwin et al., Advances in l-leterocyclic Chemistry 10, 149 (1969)].

Mild hydrolysis of 2,4-dichloro-pyrido[3,2- d]pyrimidine with one equivalent of an alkali metal hydroxide at relatively low temperatures yields 2-chloro- 4-hydroxy-pyrido [3,2-d1pyrimidine, which is subsequently reacted with a corresponding amine at more elevated temperatures to yield a corresponding 2-amino-4-hydroxy-substituted Pyrido[ 3,2- d]pyrimidine which, in turn, is subsequently converted into the corresponding 2-amino-4-halo-substituted pyrido[3,2-d]pyrimidine of the formula 11 by conventional methods.

A halo-substituted pyrido[3,2-d]pyrimidine of the formula 11 may be converted into a correspondingly substituted mercaptoor hydroxy-pyrido[3,2- d]pyrimidine of the formula 11 by reaction with a corresponding mercaptoor hydroxy-compound in the presence of a strong base. A mercapto-substituted pyrido[3,2-d]pyrimidine of the formula 11 thus obtained may, in turn, be converted into a corresponding sulfinylor sulfonylsubstituted pyrid0[3,2-d]pyrimidine of the formula 11 by oxidation.

A starting compound of the formula IV may be obtained by method A above.

The following examples further illustrate the present invention and will enable others skilled in the art to understand it more completely. It should be understood,

however, that the invention is not limited solely to the particular examples given below. Preparation of a starting compound of the formula IV.

EXAMPLE A 2-Piperazino -4-ethylmercapto-pyrido[3,2- dlpyrimidine.

(a) 2-Chloro-4-ethylmercapto-pyrido[ 3 ,2- d]pyrimidine A suspension of 15 gm (0.075 mol) of 2,4- dichloropyrido[3,2-d]pyrimidine in 100 ml of acetone at -40C was admixed with a solution of 3.2 gm (0.08 mol) of sodium hydroxide and 4.9 gm (5.8 ml) of ethylmercaptan in 25 ml of water, and the mixture was stirred for two hours at room temperature. Thereafter, 200 ml of water were added to the reaction mixture, and theprecipitate formed thereby was collected and recrystallized from petroleum ether, yielding 11.0 gm (65 percent of theory) of 2-chloro-4-ethylmercaptopyrido[3,2-d]pyrimidine, m.p. ll03C.

(b) 2-Piperazino-4-ethylmercapto-pyrido[3,2- d]pyrimidine A mixture consisting of'S gm (0.022 mol) of the end product obtained in (a), 4.7 gm (0.055 mol) of anhydrous piperazine and 20 ml of dioxane was heated at its boiling point for minutes. Thereafter, the resulting solution was evaporated, the residue was taken up in 2N acetic acid, and the solution was filtered. The filtrate was made alkaline with 4N sodium hydroxide, and the precipitate formed thereby was collected and recrystallized from benzene/cyclohexane, yielding 3.6 gm (59 percent of theory) of 2-piperazino-4-ethylmercapto-pyrido[3,2-d]pyrimidine, m.p. 98101C.

Preparation of end products of the formula 1.

EXAMPLE 1 2 Piperazino 4 thiomorpholino pyrid0[3,2-d| pyrimidine by method A 18.0 gm (0.0715 mol) of 2-chloro-4-thiomorpholinopyrido[3,2-d]pyrimidinc (m.p. l62-164C), encased in a liquid-permeable envelope, were extracted therefrom by placing it into a boiling solution of 30.6 gm (0.356 mol) of anhydrous piperazine in ml of dioxane; the extraction was complete after about 5 hours. Thereafter, the reaction solution was evaporated, the residue was taken up in a mixture of water and benzene, and the organic phase was separated and evaporated. The residue was dissolved in 300 m1 of methanol, the resulting solution was filtered, the filtrate was again evaporated, and the residue was recrystallized from 600 ml of cyclohexane. Upon working up the mother liquors, a total of 17.3 gm (76.5 percent of theory) of the compound of the formula I (if) having a melting point of 144-145C, was obtained.

lts dihydrochloride hydrate had a melting point of 220225C (decomp; recrystallized from ethanol);

lts dihydrobromide hydrate had a melting point of ll4l 15C (decomp.);

lts maleate had a melting point of -l9lC (recrystallized from methanol).

The same compound was obtained from the same reactants by boiling for one hour in 1,2-dimethoxyethane; yielding 72 percent of theory, m.p. 143-144C.

EXAMPLE 2 Using a procedure analogous to that described in Example 1, 2-(N-carbethoxy-piperazino)-4-thiomorpholino-pyrido[3,2-d]pyrimidine, m.p. l53-154C (recrystallized from ethanol, of the formula NO-COO c 1t so 1 was prepared from 2-chloro-4-thiomorpholinopyrido[3,2-d]pyrimidine and N-carbethoxy-piperazine. The yield was 83 percent of theory. 7

EXAMPLE 3 Using a procedure analogous to that described in Example l, 2-(N '-benzoyl-piperazino )-4-thiomorpholinopyrido [3,2-d]pyrimidine, m.p. l68-l70C (recrystallizedfrom isopropanol), of the formula was prepared from 2-chloro-4-thiomorpholinopyrido[3,2-d]pyrimidine and N-benzoyl-piperazine. The yield was 85 percent of theory.

EXAMPLE 4 Using a procedure analogous to that described in Example l, 2-[N-(p-toluene-sulfonyl)-piperazino[-4- thiomorpholino-pyrido[3,2-dlpyrimidine, m.p. l95-l96C (recrystallized from benzene/petroleum ether), of the formula was from prepared pyrido[3,2-d]pyrimidine and N-(p-toluene-sulfonyl)- piperazine. The yield was 76 percent of theory.

EXAMPLE 5 Using a procedure analogous to that described in Example l, 2-(N'-methyl-piperazino)-4-thiomorpholin0- pyrido [3,2-dlpyrimidine, m.p. l33l35C (recrystallized from ethyl acetate), of the formula from pyridol 3,2-dlpyrimidine and N-methylpiperazine. The

was prepared 2-chloro-4-thiomorpholino- 2-chloro-4-thiomorpholino-' yield was 69 percent of theory. Its dihydrochloride had a melting point of 272-'-274C (dec0mp.).

EXAMPLE 6 Using a procedure analogous to that described in Example 1 l, 2-(dipropanol-amino)-4-thiomorpholinopyrido[3,2-d]pyrimidine, m.p. ll5-l 16C (recrystallized from ethyl acetate), of the formula was prepared from 2-chloro-4-thiomorpholinopyrido[3,2-d]pyrimidine and dipropanol-amine. The yield was 50 percent of theory. lts hydrochloride had a melting point of l86188C (recrystallized from npropanol).

CH2-CH2-CH2OH CH2-CH2-CH2OH EXAMPLE 7 Using a procedure analogous to that described in Example l, 2-(diethanol-amino)-4-thiomorpholinopyrido[3,2-d]pyrimidine, m.p. ll4-l 15C (recrystallized from ethyl acetate), of the formula pyrido[3,2-d]pyrimidine and diet'hanol-amine. The yield was 72 percent of theory. Its hydrochloride had a melting point of 2 l 2-2 l 3C (decomp; recrystallized from methanol).

EXAMPLE 8 2-Piperazino-4-( l '-oxido-thiomorpholino)-pyrldo[3,2- d]pyrimidine by method A 24.0 gm (0.085 mol) of 2-chloro-4-( l '-oxidothiomorpholino)-pyrido[3,2-d]pyrimidine (mp. l98200C, decomp.) were added gradually over a period of one hour to a boiling solution. of 36.6 gm (0.425

mol) of anhydrous piperazine in 240 ml of'dioxane (or 1,2-dimethoxy-ethane), and the resulting mixture was refluxed for 2 V2 hours. Thereafter, the reaction solution was evaporated, the residue was dissolved in ml of hot water, and the small amount of insoluble material was filtered off. The filtrate was extracted eight times with 50 ml each of a mixture of chloroform and methanol (4:1), and each extract was washed twice with 50 ml of water each. The organic phases thus freed from excess piperazine were combined, dried and evaporated. The residue was digested with benzene. collected by vacuum filtration and then recrystallized from ethyl acetate, yielding 23.8 gm (84 percent of theory) of the compound of the formula having a melting point of 200-202C. lts dihydrochloride had a melting point of 305-307C (decomp.; recrystallized from 80 percent ethanol).

EXAMPLE 9 EXAMPLE Using a procedure analogous to that described in Example l, 2-(dipropanol-amino)-4-( 1'-oxido-thiomorpholino-pyrido[3,2-d]pyrimidine, m.p. 146l48C (recrystallized from benzene), was prepared from 2- chloro 4 (1- oxido thiomorpholino) pyrido[3,2 dlpyrimidine and dipropanol-amine. Its hydrochloride had a melting point of 202-203C (recrystallized from ethanol/ether). The yield was 73 percent of theory.

EXAMPLE 11 Using a procedure analogous to that described in Example 1, 2-(N-ethanol-hexanolamino)-4-(l'-oxidothiomorpholino)-pyrido[3,2-dlpyrimidine was prepared from 2-chloro-4-(l'-oxido-thiomorpholino)- pyrido[3,2-d]pyrimidine and N-ethanol-hexanolamine. its hydrochloride had a melting point of l92-193C (recrystallized from ethanol/ether). The yield was 71 percent of theory.

EXAMPLE 12 Using a procedure analogous to that described in Example l, 2-morpholino-4-( l '-oxi do-thiomorpholinopyrido[3,2-d]pyrimidine, m.p. 2l8-220C, of the formula 8 was prepared from 2-chloro-4-( l '-oxitiothiomorpholino)-pyridol3,2-d1pyrimidine and morpholine. lts hydrochloride had a melting point of 262-263C (decomp; recrystallized from ethanol). The yield was 83 percent of theory.

EXAMPLE 13 Using a procedure analogous to that described in Example 8, 2-ethylenediamino-4-(l'-oxido-thiomorpholinopyrido[3,2-d]pyrimidine of the formula was prepared from 2-chloro-4-( 1-oxidothiomorpholino)-pyrido[3,2-di]pyrimidine and ethylenediamine. lts dihydrochloride had a melting point of 299300C (decomp.; recrystallized from methanol/- water 9:12). The yield was 17.5 percent of theory).

EXAMPLE 14 Using a procedure analogous to that described in Example 8, 2-piperazino-4-(1roxido-2-methylthiomorpholino-pyrido[3,2-d]pyrmidine, m.p. 167C (recrystallized from benzene/cyclohexane), of the formula was prepared from 2-chloro-4-( l '-oxido-2-methylthiomorpholino )-pyrido[ 3 ,2-d]pyrimidine, m.p. 196199C and piperazine. The yield was 48 percent of theory.

EXAMPLE 15 Using a procedure analogous to that described in Example l, 2-piperazino-4-morpholino-pyridol 3 ,2- d]pyrimidine, m.p. l67l68C (recrystallized from benzene), of the formula was prepared from 2-chloro-4-morpholino-pyrido['3,2- d]pyrimidine, m.p. l74-l75C, and piperazine hexahydrate in glycol dimethylether. lts dihydrochloride hydrate had a melting point of 28 l-283C (recrystallized from ethanol). The yield was 74 percent of theory.

EXAMPLE 16 having a melting point of l42-l 43C. lts dihydrochloride had a melting point of 264267C (recrystallized from ethanol).

EXAMPLE 17 Using a procedure analogous to that described in Example 16, Z-(diethanol-amino )-4-morpholinopyrido[3,2-d]pyrimidine, m.p. 143-l45C (recrystallized from benzene or ethyl acetate), was prepared from 2-chloro-4-morpholino-pyrido[3,2-d]pyrmidine and diethanolamine. The yield was 38.6 percent of theory.

EXAMPLE 18 Using a procedure analogous to that described in Example l, 2-(dipropanol-amino)-4-morpholinopyrido[3,2-d]pyrimidene, m.p. ll2-l 13C (recrystallized from carbon tetrachloride), was prepared from 2-chloro-4-morpholino-pyrido[3,2-d1pyrimidene and dipropanolamine.

EXAMPLE 19 Using a procedure analogous to. that describedin Example l, 2-(N-ethanol-hexanolamino)-4-rnorpholinopyrido[3,2-d]pyrimidine, m.p. IOU-102C (recrystallized from ethyl acetate), was prepared from 2-chloro- '4-morpholino-pyrido[3 ,2-d1pyrimidine and N-ethanolhexanolamine. The yield was 53 percent of theory.

EXAMPLE 20 Using a procedure analogous to that described in Example l, (+)-2-piperazino-4-(2'-methyl-morpholino )-v 10 pyrido[3,2-d]pyrimidine, m.p. l35l37C (recrystallized from cyclohexane), specificrotation [01],, +43? (c 1.0, methanol), was prepared from (+)-2- chloro 4 (2 methyl morpholino) pyrido[3,2 d] pyrimidine, m.p. 9698C, and piperazine. The yield was percent of theory. lts dihydrochloride semihydrate had a melting point of 172C (recrystallized from ethanol) and a specific rotation [a],, +42 (c 0.91, water).

EXAMPLE 21 Using a procedure analogous to that described in Example l, (-)-2-piperazino-4-(2-methyl-morpholino)- pyrido[3,2-d]pyrimidine,' m.p. l34'l36C (recrystallized from cyclohexane), specific rotation [01],, -43.5 (c 1.0, methanol), was prepared from (-)-2- chloro 4 (2- methyl morpholino) pyrido[3,2 d] plti iqi s ll-a. 99C; da psra n e y e w 73 percent of theory. Its dihydrochloride semihydrate had a melting point of l70-l72C (recrystallized from ethanol) and a specific rotation [a] -39.5 (c 0.75, water).

EXAMPLE 22 Using a procedure analogous to that described in Example l, 2-piperazino-4-piperidino-pyrido[3,2- d]pyrimidine, m.p. 1l3l l4.5C (recrystallized from cyclohexane), of the formula was prepared from 2chloro-4-piperidino-pyrido[3,2- d]pyrimidine, m.p. ll5-l 18C, and piperazine in glycol dimethylether. The yield was 72 percent of theory.

EXAMPLE 23 Using a procedure analogous to that described in Example l, 2-(dipropano1-amino)-4-piperidinopyrido[3,2-d]pyrimidine, m.p. 98-l00C (recrystallized from ethylacetate/petroleum ether 2:1), was prepared from 2-chloro-4-piperidino-pyrido[3,2- dlpyrimidine and dipropanolamine. The yield was 66 percent of theory.

EXAMPLE 24 Using a procedure analogous to that described in Example l, 2-piperazino-4-( l ',l '-dioxido-thiomor pholino)-pyrido[3,2-d]pyrimidine, m.p. 2082l0C (recrystallized from ethanol), of the formula EXAMPLE 25 Using a procedure analogous to that described in Example l 2-thiomorpholino-4-( N -carbe'thoxypiperazino)-pyrido[ 3 ,2-d1pyrimidine, m.p. l7l.5172.5C (recrystallized from ethyl acetate), of the formula A Y was prepared from ,2-chloro-4-(N'-carbethoxypiperazino)-pyrido[3,2-d1pyrimidine, m.p. l20-l23C, and thiomorpholine. The yield was 80 percent of theory.

EXAMPLE 26 Using a procedure analogous to that described in Example l, 2-( l -oxido-thiomorpholino)-4-piperazinopyrido[3,2-d]pyrimidine was prepared from 2-(loxido thiomorpholino) thiomorpholino) 4 ethylmercapto-pyrido[3,2-d]pyrimidine (m.p. 199200C) and piperazine at 200C. Its dihydrochloride had a melting point of 294-296C. The yield was 18 percent of theory. 7 V 7 Example 27 2-Thiomorpholino-4-piperazino-pyrido[ 3 ,2- d]pyrimidine by method B 9 gm of finely powered potassium hydroxide were dissolved in 120 ml of boiling isopropanol, the resulting solution was admixed with 12.6 gm of 2- thiomorpholino 4 (N- carbethoxy piperazino) pyrido[3,2-pyrimidine, and the mixture was refluxed for 8 hours. Thereafter, the reaction solution wasevaporated, the residue was admixed with water, and the aqueous mixture was extracted with chloroform. The organic extract solution was washed with water, dried and evaporated, the residue was taken up in hot benzene, the insoluble brown matter was filtered off, and the'filtratewas again evaporated. The residue was recrystallized from a small amount of methanol, yielding 6.1 gm (60 percent of theory) of the compound of the formula 12 having a melting point of l56158C. lts dihydrochloride, precipitated from ethanol with ethereal hydrochloric acid, had a melting point of 283" -285C (recrystallized from n-propanol).

EXAMPLE 28 Using a procedure analogous to that described in Example l, 2-(N'-benzoyl-piperazino)-4-( l '-oxidothiomorpholino)-pyrido[ 3 ,2-]pyrimidine, m.p. 256258C (recrystallized from ethyl acetate), was prepared from 2-chloro-4-( l -oxidothiomorpholino pyrido[3,2-d]pyrimidine, m.p. l98-200C (decomp.), and N-benzoyl-piperazine.

EXAMPLE 29 EXAMPLE 30 Using a procedure analogous to that described in Example l, 2,4-bis-thiomorpholino-pyridol 3 ,2-

d]pyrimidine, m.p. l34-l35C (recrystallized from ethanol), of the formula UFO was prepared from 2-chloro-4-thiomorpholinopyrido[3,2-d]pyrimidine and thiomorpholine. The yield was 49 percent of theory.

EXAMPLE 3 l 2,4-Bis-( N '-carbethoxy-piperazino )-pyrido[ 3 ,2- d]pyrimidine by method A A solution of 2.0 gm (l0 millimols) of 2,4- dichloropyrido[3,2-d]pyrimidine in 10 ml of dioxane was admixed with 7.1 gm (45 millimols) of N-carbethoxy-piperazine, and the mixture was stirred for 30 minutes at room temperature; however, the 2- qhlem 4-10 s h thq Pipgrazino) BX Q BZ d]pyrimidine formed thereby was not isolated. The reaction mixture was then refluxed for 4 hours, the resulting reaction solution was evaporated, and the residue was admixed with water, whereby the reaction product slowly crystallized out. The crystals were collected by vacuum filtration, dried and extracted with a large amount of boiling petroleum ether, yielding 2.2 gm (50% of theory) of the compound of the formula at room temperature,,then diluted with water, and the precipitate formed thereby was collected and recrystallized from isopropanol, yielding 4,6 gm (65 percent'of theory) of the compound of the formula having a melting point of l58-l59C.

EXAMPLE 33 2-(N'-Methanesulfonyl-piperazino)-4-thiomorpholinopyrido[3,2-d]pyrimidine, m.p. 2l8-2l9.C (recrystallized from benzene), of the formula was prepared in a manner analogous to Example 32 from 2-piperazino-4-th'iomorph0lino-pyrido[3,2- d]pyrimidine and methanesulfonyl chloride in dioxane in the presence of pyridine. The yield was 66 percent of theory.

EXAMPLE 34 2-(N'-Formyl-piperazino)-4-thiomorpholinopyrido[ 3,2-d1pyrimidine A mixture consisting of 9.5 gm of 2-piperazino-4- thiomorpholino-pyridol3,2-dlpyrimidine, 7.5 gm of formic acid and 120 ml of toluene was boiled for 90 .minutes in a flask provided with a water separator.

Thereafter, the toluene was distilled off in vacuo, the residuewas admixed with ethyl acetate,and the mixture was refluxed. The insoluble matter was filtered off,

the filtrate was admixed with petroleum ether, and the precipitate formed thereby 'was collected and recrystallized from isopropanol, yielding 7.3 gm (7] percent of 'theory) of the compound'of the formula having a melting point of 129.5-13lC.

EXAMPLE 35 2 '(N- Formyl piperazine); (if oxido thi0mor- .pholino)-pyrido[ 3,2-d]pyrimidine 1 A mixture consisting of 5.6 gm (20 millimols) of 2- chloro-4-(l '-oxido-thiomorpholino|)-pyrido[ 3.,2-

d]pyi'imidine, 4.8 gm (42 millimols) of N-formylpiperazine and 40 ml of. dioxane was refluxed for 4 hours'Thereafter, the solvent was distilled off in vacuo, the residue was admixed with water, the aqueous phase was extracted with methylene chloride, and the organic extract was washed with water, dried, filtered and evaporated in vacuo. The residue was recrystalized from 35 ml of ethyl acetate, yielding 5.6 gm (77.8 percent of theory) of the above-named product having a melting point of l6l-163C; upon further recrystallization from isopropanol the producthad a melting point of l65-l66C.

EXAMPLE 36 2 (N'- Aminocarbonyl piperazine); 4; l oxido thiomorpho lino)-pyrido [3,2-dlpyrimidine A solution of 8.0 gm (20 millimols) of 2-piperazino- 4-( l -oxido-thiomorpholino)-pyrido[ 3,2-d]pyrimidine dihydrochloride in 40 ml of water was admixed with 1.9 gm (23 millimols) of potassium cyanate, and the resulting mixture was allowed to stancl for 15 minutes at room temperature and was then heated for 30 minutes at 40C. Thereafter, the reaction solution was made alkaline with sodium hydroxide, and the precipitate formed thereby was collected by vacuum filtration, yielding 5.8 gm of the compound of the formula having a melting point of 230-231C.

lts hydrochloride, m.p. 190-192C (decomp), prepared by treating the freebase with ethanolic hydrochloric acid and recrystallizing the product from ethanol/water (9 1), was obtained with a yield of 6 gm (73 percent of theory). 1

EXAMPLE 371 2 Diethanolamino -f} (l oxido thiomorpholino) pyrido[3,2-d] pyrimidine hydrochloride A mixture consisting of 5.6 gm millimols) of 2- chloro 4 (1- oxido thiomorpholino) pyrido[3,2 d]pyrimidine, 5.2 gm (50 millimols) of diethanolamine and 40 ml of dioxane was refluxed for 6 hours. Thereafter, the reaction solution was evaporated in vacuo, the residue was admixed with water, the aqueous mixture was extracted with chloroform, and the extract solution was evaporated. The residue was dissolved in ethanol, the resulting solution was acidified with ethanolic hydrochloric acid, and the crystalline precipitate formed .thereby was collected, yielding 5.8 gm (75 percent of theory) of the above-named hydrochloride havidg a melting point of 232-233C.

EXAMPLE 38 2-Piperazino-4-(1- oxido thiomorpholino)-6-methylpyrido[3,2-]pyrimidine by method A 2.6 gm (9.5 millimols) of 2-chloro-4-(1'-oxidothiomorpholino) 6 methyl pyrido[3,2 -d]pyrimidine (m.p. 228229C), encased in a liquid-permeable envelope, were extracted therefrom by placing it into a refluxing solution of 3.9 gm (45 millimols) of anhydrous piperazine in ml of dioxane; the extraction was complete after about 2 A hours. Thereafter, the resulting solution was evaporated, the residue was taken up in water, and the precipitate formed thereby was filtered off. The filtrate was extracted ten times with 20 ml each of chloroform/methanol (3:1), and each extract was washed twice with 20 ml of water each. The washed extracts were combined, dried and evaporated, yielding 2.8 gm (68 percent of theory) of'the compound of the formula having a melting point of l92194C.

lts dihydrochloridc, m.p. 222-224C (decomp.), was obtained by adding isopropanolic hydrochloric acid to a solution of the free base in isopropanol.

EXAMPLE 39 2-(N'- Benzoyl piperazino) 4 (loxido thiomorphoIino)-6-methyl-pyridol3.Z-dIpyrimidinc by method A"...

A mixtureconsisting of 2.96 gm (1O millimols) of 2- chloro 4 (1- oxido thiomorpholino) 6 methyl pyrido[3,2-d]pyrimidine, 5.70 gm (30 millimols) of N-benzoyl-piperazine and 20 ml of dioxanc was refluxed for 3 hours. Thereafter, the reaction solution was diluted with water, and the precipitate formed thereby was collected by vacuum filtration and recrystallized from ethanol. yielding 88 percent of theory of the compound of the formula having a melting point of 230-231C.

EXAMPLE 40 Using a procedure analogous to that described in Example 38, 2-piperazino-4-thiomorpholino-6-methylpyrido [3,2-d1pyrididine was prepared from 2-chloro- 4 thiomorpholino-6-methyl;pyrido[3,Z dJ pyrimidine, m.p. 150-151C, and piperazine hexahydrate at 60-l00C. The yield was 26 percent of theory. Its hydrochloride hydrate had a melting point of 304-306C (decomp; recrystallized from methanol).

EXAMPLE 41 Using a procedure analogous to that described in Example 39, 2-(N'-carbethoxy-piperazino)-4- hiome ph q- 6 me hy pyr slQB.Zztll p m.p. 1 15-1 16C. (recrystalized from cyclohexane was prepared from 2- chloro-4-thiomorpholino-6-methy1- pyrido[3,2-d]pyrimidine and N-carbethoxy-piperazine in dioxane. The yield was 71 percent of theory.

EXAMPLE 42 Using a procedure analogous to that described in Example 38, 2-piperazino-4( 1,1-dioxidothiomorpholino)-6 -methyl-pyrido[3,2-d]pyrimidine, m.p. 190192C (recrystallized from water), was prepared from 2-chloro-4-( 1',1 -dioxide-thiomorpholino)- 6-methyl-pyrido[3,2-d1pyrimidine, m.p. 286-288C, and piperazine in glycol dimethylether. The yield was percent of theory. Its dihydrochloride had a melting point of 235C [decomp.; recrystallized from ethanol/- water (:15)].

EXAMPLE 43 Using a procedure analogous to that described in Example 39. 2-thiomorpholino-4-(N'-carhethoxypiperazino)-6-methyl-pyrido[3,2-d1pyrimidine, m.p. l57158C (recrystallized from ethyl acetate), was

prepared from 2-chloro-4-(N-carbethoxy-piperazino)- 6-methyl-pyrido[3,2-dlpyrimidine, m.p. l72-l73C, and thiomorpholine in boiling dioxane. The yield was 90 percent of theory.

EXAMPLE 44 EXAMPLE 45 Using a procedure analogous to that described in Example 39, 2-(N'-methyl-piperazino)-4-morpho1ino-6- methyl-pyrido[3,2-d]pyrimidine, m.p. 128-l30C (recrystallized from petroleum ether), was prepared from 2-chloro-4-morpholino-6-methyl-pyrido[3,2-d] pyrimidine, m.p. 146-149C, and excess N-methylpiperazine at l60C The yie1d wast 3 6 percent of theory. its dihydrochloride had a melting point of 202-204C (decomp; recrystallized. from isopropanol).

EXAMPLE 46 2,4 Bis thiomorpholino 6 methyl pyrido[3,2 d] y im s n yrnet q Am t e,

A solution of 1 gm (3.6 millimols) of 2,4-dichloro6- methyl-pyrido[3,2-d1pyrimidine (m.p. 152l53C; literature mp. 138C) in 10 ml of dioxane was admixed with 1.8 gm (l8 millimols) of thiomorpholine, and the mixture was allowed to stand overnight at room temperature and was then refluxed for 5 minutes. Thereafter, the reaction solution was diluted with water, the aqueous mixture was extracted with ethyl acetate, the extract solution was evaporated, and the residue was recrystallized once from petroleum ether and then once from ethanol, yeilding 600 mgm (50 percent of theory) of the compound of the formula having a melting point of 1 l2-l 14C.

Example 47 l was taken upon in a mixture of chloroform and water.

The organic phase was separated and evaporated, the residue was dissolved in ethanol, the solution was acidihaving a melting point of 295-297C (decomp.)

The compounds according to the present invention, that is, those embraced by formula 1 and their nontoxic, pharmacologically acceptable acid addition salts, have useful pharmacodynamic properties. More particularly, the compounds of the instant invention exhibit a very strong inhibiting action upon thrombocyte aggregation and adhesiveness (platelet stickiness), as well as hypotensive activities, in warm-blooded animals, such as mice, cats and dogs. For instance, the hypotensive activity is particularly pronounced in 4-piperazino- 2 (loxido thiomorpholino) pyrido[3,2-d]pyrimidine, 4 piperazino 2 thiomorpholino pyrido[3,2- d] pyrimidine and 2-piperazino-4-(l-oxido-thiomorpholino)-pyrido[3,Z-dIpyrimidine.

The inhibiting action upon thrombocyte aggregation was ascertained by the method of Born and Cross, J. Physiol. 170, 397 (1964), or by the method of K. Breddin, Schweiz. Med. Wochenschr. 95, 655-660 (1965).

The inhibiting effect upon the platelet stickiness was determined by means of the so-called retention test according to Morris [See E. Deutsclh et al, 1. internationales Symposium uber Stoffwechsel and Membranpermeabilitat von Erythrocyten and Thrombocyten, Vienna, Austria (1969); Georg Thieme Verlag, Stuttgart, Germany].

The prolonging effect upon the bleeding time was ascertained by the method of Duke, J, Amer. Med. Assoc. 15, 1185 (1910).

The hypotensive tests were performed on anesthetized cats and dogs by the method of Eckenoff, Amer. J. Physiol. 148, 582 (1947).

The table below shows the results obtained from the tests for thrombocyte aggregation inhibition according to the method of Morris and from the tests for prolongation of the bleeding time for a number of representative compounds according to the present invention, namely:

2-piperazino-4-thiomorpholinopyrido[3,2- d]pyrimidine maleate,

2-(N-methy1-piperazino)-4-thiomorpholinopyrido[ 3,2-d]pyrimidine dihydrochloride,

2-piperazino-4-( 1 -oxido-thiomorpholino)- pyrido[3,2-d]pyrimidine dihydrochloride, D 2-(N-methyl-piperazino)-4-( l -oxidothiomorpholino)-pyrido[3,2-d]pyrimidine dihydrochloride,

E 2-(dipropanol-amino)-4-(l'-oxido-thiomopholino)-pyrido[ 3,2-d1pyrimidine hydrochloride,

= 2-(N-ethanol-hexanolamino)-4-( l -oxidothiomorpholino)-pyrido[3,2-d]pyrimidine hydrochloride,

2-piperazino-4-( l '-oxido-2'-methyl-thiomorpholino)-pyrido[3,2-d]pyrimidine dihydrochloride, H

2-piperazino-4-morpholino-pyrido[ 3 ,2- d]pyrimidine dihydrochloride, l 2-(N'-methyl-piperazino)-4-morpholinopyrido[3,2-d]pyrimidine dihydrochloride, J 2-(dipropanol-amino)-4-morpholino-pyrido[3,2-

d]pyrimidine dihydrochloride,

2-piperazino-4-piperidino-pyrido[3,2- d]pyrimidine dihydrochloride, L 2-(dipropanol-amino)-4-piperidino-pyrido[3,2-

d]pyrimidine hydrochloride, M 2-piperazino-4-( 1 1'-dioxide-thiomorpholino)- pyrido[ 3,2-d1pyrimidine dihydrochloride,

2-thiomorpholino-4-piperazino-pyrido[3,2- dlpyrimidine dihydrochloride,

2-( l '-oxido-thiomorpholino)-4-piperazinopyrido[ 3 ,2-d]pyrimidine dihydrochloride,

2-piperazino-4-( l '-oxido-thiomorpholino)-6- methyl-pyrido[3,2-d]pyrimicline dihydrochloride and Q 2-thiomorpholino-4-piperazino-6-methylpyrido[3,2-d]pyrimidine dihydrochloride.

1. To determine the inhibiting action of the test compound upon thrombocyte aggregation, 1 ml of human blood is pipetted into small test tubes, and the test compound is added to a final concentration of 5X10 moi/- liter. The tubes are incubated for minutes at 37C. 1 gm of glass beads (glass beads for gaschromatography) is added to half of the tubes. Finally the closed tubes are attached to a vertical wheel and rotated for 1 minute. By this means good contact is obtained between the glass beads and the blood. The tubes are then allowed to stand at room temperature for another hour, after which time a satisfactory sedimentation of erythrocytes has taken place. 0.01 ml of the supernatant plasma is removed, diluted to 1: 8,000 with celloscope solution, and the platelet count is read in the celloscope. The percent reduction in the stickiness due to the presence of the substance (compared to tubes without glass beads) is measured and the average of four-six determinations is taken.

2. To determine the bleeding time 10 mgm/kg of the test compound is given per os to non-anesthetized mice. After one hour, about 0.5 mm is cut off from the tail of each animal. The exuded blood is soaked up with filter paper every 30 seconds. The number of drops of blood so obtained is used as a measure for the bleeding time compared to untreated animals (5 animals/test).

3. The acute toxicity of some of the compounds for orientation (observation time: '14 days) was determined on mice, or the LD was'calculated from the percentage of animals which died after different doses within the observation time [see J. Pharmacol. exper. Therap. 96, 99( 1949)].

TABLE Com- Reduction in Prolongation of LD pound Stickiness Bleeding Time mg/kg p.o

M 88 98 250 (0 out of l0 animals died) N 77 98 250 (0 out of 10 animals died) 0 98 35 250 (0 out of 10 animals died) For pharmaceutical purposes thecompounds according to the present invention are administered to warmblooded animals perorally or parenterally as active ingredients in customary dosage unit compositions, that is, compositions in dosage unit form consisting essentially of an inert pharmaceutical carrier and one effective dosage unit of the active ingredient, such as tablets, coated pills, capsules, wafers, powders, solutions, suspensions, emulsions, syrups, suppositories and the like. One effective dosage unit of the compounds according to the present invention is from 0.083 to 1.67 mgm/kg body weight, preferably 0.16 to 0.84 mgm/kg body weight. The daily dose rate is from 1.66 to 3.34 mgm/kg body weight.

The following examples illustrate a few pharmaceutical dosage unit compositions comprising a compound of the present invention as an active ingredient and represent the best modes contemplated of putting the invention into practical use. The parts are parts by weight unless otherwise specified.

EXAMPLE 48 Tablets The tablet composition is compounded from the following ingredients:

2-Piperazino-4-thiomorpholinopyrido[ 3,2-dlpyrimidine maleate 30.0 parts Lactose 38.0 do.

Potato starch 26.0 do.

Polyvinylpyrrolidone 5.0 do.

Magnesium stearate 1.0 do.

Total 100.0 parts Preparation:

The pyridopyrimidine salt is intimately admixed with the lactose and the potato starch, the mixture is uniformly moistened with an ethanolic 20 percent solution of the polyvinylpyrrolidone, the moist mass is forced through a 1.5 mm-mesh screen, and the resulting granulate is dried at 45C. and again passed through a 1.0 mm-mesh screen. The dry granulate thus obtained is admixed with the magnesium stearate, and the composition is compressed into 100 mgm-tablets in a conventional tablet making machine. Each tablet contains 30 mgm of the pyridopyrimidine salt and is an oral dosage 21 unit composition with effective thrombocyte aggregation and stickiness inhibiting action.

EXAMPLE 49 Coated Pills The pill core composition is compounded from the following ingredients: I

2-Piperazino-4-( l '-oxido-thiomorpholino)-pyrido[ 3 2d] pyrimidine dihydrochloride 15.0 parts Lactose 14.0 do. Corn starch l 8.0 do. Polyvinylpyrrolidone 2.5 do. Magnesium stearute 0.5 do.

Total 7 10.0 parts EXAMPLE so Hypodermic Solution The solution is compounded from the following ingredients:

2 Piperazino-4-( l '-oxido'2' methyl-thiomorpholino)-Pyrido [3,2-d1pyrimidine dihydrochloride 10.0 parts Polyethyleneglycol 600 100.0 do. Distilled Water g.s.ad 2000 do. by vol.

Preparation:

The polyethyleneglycol and the pyridopyrimidine salt are dissolved in a sufficient amount of distilled water which had previously been boiled and cooled in an atmosphere of nitrogen; the dissolution is also carried out in an atmosphere of nitrogen. The resulting solution is diluted to the indicated volume with additional preheated distilled water, and the resulting solution is filled, again in an atmosphere of nitrogen, into brown 2 cc-ampules which are then sterilized for 20 minutes at 120C. and subsequently sealed. The entire operation must be performed in diffused light. Each ampule contains 10 mgm of the pyridopyrimidine salt, and the contents thereof are an injectable dosage unit composition with effective thrombocyte aggregation and stickness inhibiting action.

EXAMPLE 51 Drop Solution v The solution is compounded from the following ingredients:

2-Piperazino-4-morpholinopyridol 3.2-D lpyrimidine Preparation:

The sorbic acid is dissolved in the ethanol, the solution is diluted-with an equal volume of distilled water, and'the pyridopyrimidinesalt is dissolved in the aqueous mixture (solution 1). The cane sugar is dissolved in the remaining amount of distilled water (solution 2).

other pyridopyrimidines embraced by formula 1 or a nontoxic acid addition salt thereof is substituted for the particular pyridopyrimidine in Examples 48 through 51. Likewise, the amount of active ingredient in these illustrative examples may be varied to achieve the dos age unit range set forth above, and the amounts and nature of the inert pharmaceutical carrier ingredients may be varied to meet particular requirements.

While the present invention has been illustrated with the aid of certain specific embodiments thereof, itwill be readily apparent to others skilled in the art that the invention is not limited to these particular embodiments, and that various changes and modifications may be made without departing from the spirit of the invention or the scope of the appended claims.

We claim:

1. A compound of the formula wherein R and R are each morpholino, thiomorpholino, l-oxido-thiomorpholino, thiomorpholino or piperidino, where each of these may optionally have a methyl substitutent attached thereto; piperazino; N'-formyl -piperazino; N'- acetyl-piperazino; N-carbethoxy-piperazino; N'- benzoyl-piperazino; N'-methane-sulfonylpiperazino; N-p-toluenesulfonyl-piperazino; N'- aminocarbonyl-piperazino; N-carbamoylpiperazino; N'-methyl-piperazino: di(alkanol of 2 to 6 carbon atoms)-amino; or ethylenediamino and R is hydrogen or methyl; or a non-toxic, phamiacologically acceptable acid addition salt thereof.

2. A compound according to claim 1, wherein one of R and R is unsubstituted piperazino and the other is thiomorpholino, l-oxido-thiomorpholino or l,l-dioxidothiomorpholino, where each of these may optionally be methyl-substituted, and R is hydrogen or methyl, or a non-toxic, pharmacologically acceptable acid addition salt thereof. t

3. A compound according to claim 1, which is 2- piperazino-4-thiomorpholino-pyrido[3,2-d]pyrimidine s or a non-toxic. pharmacologically acceptable acid addition salt thereof.

4. A compound according to claim I, which is 4- pipcrazino-Z-thiomorpholino-pyrido[3,2-dlpyrimidinc l,l-dioxido- 23 24 or a non-toxic, pharmacologically acceptable acid ad- 7. A compound according to claim 1, which is 2- 'dlti n l I piperazino 4 (l -o tido-thiom orpholino) 6 methylcompound w g t Clalm 1, Whlch pyrido[3,2-d]pyrimidine or a non-toxic, pharmacologp a ically acceptable acid addition salt thereof. d]pyr1m1dme oranon-toxic,pharmacologically accept- 5 8 A com ound accordin to claim 1 which is ableacid addition salt thereof. 1 I p g 6. A compound according-to claim 1, which is 4- thiomPrPholino 4 f' t f piperazino 2 (1I,oxidd thiomorpholino) pyrido[3,2- d]pyr;|midme or a non-toxic, pharmacologically acceptdlpyrir rfidine 6r a non-t oiiic, pharmacologically acceptable acid addition Salt thereofable acid addition salt thereof. 10

PO"-1050 v UNITED STATES PATENT OFFICE CERTIFICATE OF CORRELTION Patent No. 38,43,538 Dated Oct. 22, 1 1+ JOSE? NICKL, ERICH MULLER, BERTHOLD t-TARR and Inventor(s) JUber' U'oir It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

EB] "JOSE? NICKI" should read EELKTHOLD NARR-.

A r1 Col. 1, llne 59 correct "2nd 4 to read w Col. 5, line after "piperahzinc should read 'i--.

Col. 8, line 30 "B ZZ- ii" should read --3,2-d--.

f??- and F55 correct. the spelling; of p;-, rimi 3ir1e".

Col. 11, lilde +8 before pyrimidine insert 3} Col. 12, line 9 I -before "dpyrimidine" insert d Col. 17, line correct "153" to read --1.5

line 65 correct "upon" to read --up--.

Col. 21, line 52 change stick" to --sticki--.

Col. 23, line change oxide"to read --oxido- Signed and sealed this 24th day of June 1975.

(SEAL) Attest:

C. ZL-RSE-IALL DANN RUTH Q. MASON Commissioner of Patents Attesting Officer and Trademarks 

1. A COMPOUND OF THE FORMULA
 2. A compound according to claim 1, wherein one of R1 and R2 is unsubstituted piperazino and the other is thiomorpholino, 1-oxido-thiomorpholino or 1,1-dioxidothiomorpholino, where each of these may optionally be methyl-substituted, and R3 is hydrogen or methyl, or a non-toxic, pharmacologically acceptable acid addition salt thereof.
 3. A compound according to claim 1, which is 2-piperazino-4-thiomorpholino-pyrido(3,2-d)pyrimidine or a non-toxic, pharmacologically acceptable acid addition salt thereof.
 4. A compound according to claim 1, which is 4-piperazino-2-thiomorpholino-pyrido(3,2-d)pyrimidine or a non-toxic, pharmacologically acceptable acid addition salt thereof.
 5. A compound according to claim 1, which is 2-piperazino-4-(1''-oxido-thiomorpholino)-pyrido(3,2-d)pyrimidine or a non-toxic, pharmacologically acceptable acid addition salt thereof.
 6. A compound according to claim 1, which is 4-piperazino-2-(1''-oxido-thiomorpholino)-pyrido(3,2-d)pyrimidine or a non-toxic, pharmacologically acceptable acid addition salt thereof.
 7. A compound according to claim 1, which is 2-piperazino-4-(1''-oxido-thiomorpholino)-6-methyl-pyrido( 3,2-d)pyrimidine or a non-toxic, pharmacologically acceptable acid addition salt thereof.
 8. A compound according to claim 1, which is 2-thiomorpholino-4-piperazino-6-methyl-pyrido(3,2-d)pyrimidine or a non-toxic, pharmacologically acceptable acid addition salt thereof. 